A variety of methods for detecting target biomolecules such as deoxyribonucleic acid (DNA) and DNA sequencing in a sample have been developed. Among these methods, a nanopore method has been used in conjunction with a DNA detection system with high sensitivity. A nanopore DNA detection system detects DNA from a slight change in electric current which occurs when DNA translocates through nanopores to perform DNA sequencing or to determine whether double-stranded or single-stranded DNA is present.
For example, a DNA detection system includes a nanopore formed through a thin film including an insulating layer/conductive gate layer/insulating layer, upper and lower sample solution reservoirs that are formed in such a manner that the nanopore is disposed therebetween, and source and drain electrodes that are respectively put in the upper and lower sample solution reservoirs. A sample solution of an electrolyte such as KCL including target biomolecules such as DNA may be filled in the upper and lower sample solution reservoirs and the nanopore.
In this structure, when a bias is applied to the conductive gate layer, target biomolecules exhibiting an electric charge in the sample solution of an electrolyte may translocate through the nanopore. In this case, target biomolecules translocating through the nanopore may be identified or DNA sequencing may be performed by measuring an electric current between the source and drain electrodes and measuring a turn-on gate voltage applied to the conductive gate layer.
There is a need to perform more accurate measurements by increasing the sensitivity of conventional nanopore DNA detection systems. There is also a need to increase measuring speed of conventional nanopore DNA detection systems.